Volume 46, Issue 3

Macroscopic flow properties of viscoelastic surfactant solution are investigated in pressure driven pipe flow condition. We focus on an equimolar aqueous solution of cetylpyridinium chloride – sodium salicylate, which in simple shear flow exhibits a shear thinning, and at higher shear rates, a pronounced shear-thickening behavior associated with the formation of shear bands [1–6]. An ultrasound Doppler velocimetry method is used to detect these shear bands in pipe flow. The emitted ultrasonic beam is scattered by the moving sample and the time delay between emitted pulse and received echoes as well as the frequency shift is determined. This Doppler shift is related to the speed and the direction of the moving scatters and with this information, the velocity profile across the pipe is calculated [7]. The shape of the obtained velocity profile is used to determine the flow properties of the sample and the formation of shear bands at the tube's wall or within the bulk phase. For the investigated solution we do not observe shear band phenomena. This is contrary to previous investigations [5, 6, 8] where shear bands in the order of few tenth of a millimeter were found. Our results suggesting that the banded region is not detectable by the utilized UVP technique.

Neem ( Azadirecta indica ) and Karanj ( Pongamia pinnata ) oils are ecofriendly, non-toxic, completely biodegradable with antiviral, antifungal, and antibacterial properties. The dark green colour Copper(II) soaps derived from Neem and Karanj oil, their greenish brown complexes with ligand 2-amino-6-methyl benzothiazole containing nitrogen and sulphur have been synthesized and characterized by elemental analysis. IR and NMR of complexes suggest that the complexation has taken place successfully. From the analytical data the stoichiometry of the complexes has been observed to be 1:1 (metal-ligand). Copper soaps and their complexes are good anti-fungal agents. The fungi toxicities of the oils, soaps and complexes of neem and karanj have been investigated. The results indicate that the strain of Candida species is susceptible towards complexes of benzothiazole.

The purpose of the paper is to provide a non-phosphorus and nitrogen free calcium phosphate inhibitor maleic anhydride-allyloxy polyethoxy carboxylate. The approach is that synthesized monomer allyloxy polyethoxy carboxylate from allyloxy polyethoxy ether and chloracetic acid, and then prepared maleic anhydride-allyloxy polyethoxy carboxylate by free radical polymerization. Structures of allyloxy polyethoxy carboxylate and maleic anhydride-allyloxy polyethoxy carboxylate were characterized through FT-IR and 1 H-NMR. Influence of monomer mole ratio in maleic anhydride-allyloxy polyethoxy carboxylate and viscosity-average molecular weight of maleic anhydride-allyloxy polyethoxy carboxylate on its calcium phosphate inhibition performance was discussed. Calcium tolerance and calcium phosphate inhibition capability of maleic anhydride-allyloxy polyethoxy carboxylate was compared with the latest generation of calcium phosphate inhibitor maleic anhydride-ammonium allylpolyethoxy sulphate, and other two kinds of known inhibitor acrylic acid/2-hydroxypropyl acrylate and acrylic acid/acrylamido-2-methyl-1-propane sulfonic acid. As a result, monomer mole ratio and viscosity-average molecular weight has great impact on property of maleic anhydride-allyloxy polyethoxy carboxylate. Calcium tolerance and calcium phosphate inhibition of maleic anhydride-allyloxy polyethoxy carboxylate is similar to maleic anhydride-ammonium allylpolyethoxy sulphate. The results reveal that maleic anhydride-allyloxy polyethoxy carboxylate is an excellent green calcium phosphate inhibitor.

In this communication, it has been demonstrated by using electrospray ionization mass spectrometry (ESI-MS) that benzene moiety of alkylphenol ethoxylates (common non-ionic surfactants) can be a source of stacking interactions. Three cations being prone to interact with aromatic ring have been used: Cu 2+ , Ag + and tetramethylammonium cation (CH 3 ) 4 N + . Because of cation- interactions the stabilities of the complexes of alkylphenol ethoxylate with these cations have been enhanced, as evidenced by relative intensities of respective peaks in the ESI mass spectra. Oxygen atoms from ethoxylene chain interact with the cations, and these ion-dipole interactions compete with cation- interactions, therefore cation- interactions have been observed for alkylphenol ethoxylates with shorter ethoxylene chain.

A series of polymeric surfactants were prepared from O-(2-hydroxyethyl)cellulose (HEC, DS = 1) by transesterification of methyl laurate and the complex of methyl esters of rape seed oil fatty acids in the H 2 O/DMF system using microwave irradiation as heating source. The obtained derivatives were characterized by FTIR spectroscopy and viscometry, and their surfaceactive, foaming, emulsification and performance properties evaluated. The results indicate that under microwave heating water-soluble HEC-fatty acid esters with very low degree of esterification can be obtained in a few minutes and at temperatures not exceeding 100°C. The derivatives exhibited foaming ability and significant emulsifying efficiency for ‘oil in water’-type emulsions comparable to that of commercial surfactants as well as a good washing power and very high antiredeposition efficiency.

Three different forms of the surface-active domiphen cations were detected by the UV spectroscopy in aqueous solutions of domiphen bromide, eventually with KBr additive. In sufficiently dilute solutions there are free domiphen cations, which aggregate into two types of micelles at two distinct concentrations, interpreted as the first and second critical micelle concentration, cmc and cmc 2 . From the logarithmic dependences of cmc and cmc 2 on the bromide concentrations the corresponding degrees of counterion binding were estimated. Conformation analysis of the domiphen cation was performed and the packing parameters of the lowest energy conformers were calculated. The observed spectral shifts and the calculated packing parameters suggest that two conformers of domiphen cation with different arrangement of the phenoxyethyl group are responsible for the respective formation of two types of micelles.

Adsorption of cationic surfactant, cetyltrimethylammonium bromide (CTAB) on zeolite A has been investigated using surfactant-selective electrode technique. The electrode consisted of a polyvinyl chloride (PVC) membrane based on neutral ion-pair carrier complex of cetyltrimethylammonium tetraphenylborate (CTA + TPB − ). Adsorbance of CTAB on zeolite A was calculated from the potential and concentration response characteristics of the surfactant-selective electrode to get the surfactant adsorption isotherms. Adsorption isotherm of CTAB was S-shaped. The adsorbance was related to pH and electrolyte in the surfactant solutions.